Many medical procedures utilize elongate flexible guidewires for guiding the insertion of catheters, scopes or other instruments into ducts, passageways, vessels or cavities of the body. Typically, such guidewires are formed of continuous coils of thin steel wire tightly wound about a longitudinal steel core, so as to form an elongate continuous wire coil having an outer diameter of approximately 0.021-0.038 in. The outer surface of such elongate wire coil may be covered with a smooth, inert plastic coating such as a fluorocarbon (TEFLON.TM.) coating.
In many cardiovascular procedures, guidewires are often used to guide the insertion of catheters (e.g. angiographic catheters, balloon dilation catheters, pressure monitoring catheters, . . . ) to specific locations within the vascular anatomy. It is the usual practice, in such cardiovascular applications, to first insert the guidewire into a peripheral blood vessel and to subsequently advance the guidewire, under radiographic guidance, to a point at which the distal portion of the guidewire is positioned at or near a specific lesion or anatomical structure. A selected catheter or instrument (e.g. angiography catheter, balloon dilation catheter, angiosoope, . . . ) is then advanced over the pre-positioned guidewire to a position adjacent the desired operative site.
In gastroenterologic procedures, guidewires are often used to guide the advancement of catheters, endoscopic looking devices or other instruments through various portions of the gastrointestinal tract or biliary tree. In many such gastroenterologic procedures, guidewires are initially inserted through a gastroscope or duodenoscope and subsequently advanced, with or without radiographic guidance, to the desired operative location within the gastrointestinal tract or biliary tree. After the guidewire has been so positioned, a selected catheter, endoscope or other instrument (e.g. a stent, bougie or balloon for dilating a stricture) is advanced over the guidewire, to a position at or near the desired operative site.
In other procedures, such as certain laparoscopic surgical procedures, guidewires may also be transabdominally inserted, through appropriate introducers or trochars, and used to guide and position catheters, scopes and/or other instruments.
During any or all of the above described procedures, it is, from time to time, necessary or desirable to extract, remove, reposition or exchange a catheter, scope or other instrument which has already been inserted over a previously positioned guidewire. In such instances, it is highly desirable that the extraction, removal, repositioning or exchange of the catheter, scope or instrument be effected without causing withdrawal, retraction, disruption or significant movement of the pre-positioned guidewire.
In the prior art, the ability to hold a guidewire still while manipulating or exchanging a catheter, scope or other instrument which has been inserted over the guidewire has been largely dependent upon the level of accomplishment and skill of the practitioner who is conducting the procedure. To wit, the practitioner must exercise extreme caution to avoid jerking or pulling of the guidewire while carrying out the desired manipulation or exchange of the attendant catheter, scope or other instrument. In view of the potential for inadvertent movement of the guidewire, despite the best efforts of the practitioner, it is highly desirable to devise an improved guidewire which incorporates an anchoring member for anchoring and holding the guidewire in place within a tube, duct or other anatomical structure during the occasional exchange or manipulation of the attendant catheter, scope or instrument. It is further desirable that such anchoring member be incorporated into the guidewire without substantially increasing the diameter of the guidewire and without otherwise interfering with the normal mode of use of such guidewire.
The prior art has included a device for immobilizing a guidewire during use. Such device is attachable to the extracorporeal (proximal) portion of a previously inserted guidewire for the purpose of fixing or immobilizing the guidewire during or after an operative procedure. Gavant, M. L. IMPROVED GUIDEWIRE IMMOBILIZATION TECHNIQUE FOR INTERVENTIONAL PROCEDURES; American Journal of Radiology 149:629-630 (September 1987). Such device does not serve to anchor the intracorporeally inserted portion of a guidewire to a surrounding or adjacent anatomical structure.
Also, the prior art has included at least two (2) angioplasty guidewires which have inflatable balloon dilation systems mounted thereon (i.e. "balloon-on-a-wire" systems). See, Rizzo, T. F.; Ciccone, J. and Werre, R.; "DILATING GUIDE WIRE: USE OF A NEW ULTRA-LOW PROFILE PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY SYSTEM"; Catheterization and Cardiovascular Diagnosis, 16:258-262 (1989). The dilation balloons mounted on these prior art balloon-on-a-wire systems are intended for use in effecting angioplastic dilation of stenotic vascular lesions, not for anchoring. Such dilation balloons are not appropriately sized, configured or constructed to optimally carry out an anchoring or holding function. One such prior art "balloon-on-a-wire" system is commercially available under the name USCI PROBE (C. R. Bard, Inc., USCI Division, Billerica, Mass.). The other such balloon-on-a-wire system is commercially available under the name SCI-MED ACE (Sci-Med Systems Inc., Minneapolis, Minn.). Both of these prior art balloon-on-a-wire systems comprise flexible guidewires whereupon relatively large annular dilation balloons are mounted. Such balloons are sized and configured to effect a dilation function in accordance with normal transluminal angioplasty techniques. Such balloons are, however, relatively large and bulky and, even in their deflated states, such balloons substantially alter the outer surface and diameter of the guidewire body. Thus, even when deflated, the presence of such balloon could interfere with passage of the guidewire through tight openings, strictures or the like. Furthermore, because these previous balloon-on-a-wire systems are not intended for use as means for guiding the advancement of a separate catheter, scope or instrument thereover, they do require the continuous and uninterrupted attachment of a bulky hub, stopcock and/or syringe on the proximal end of the guidewire during the entire time in which the balloon is inflated. The presence of such bulky hub, stopcock and syringe on the proximal end of the guidewire essentially precludes the passage of a catheter, scope or other instrument over the proximal end of the guidewire. Furthermore, if the attendant hub, stopcock and/or syringe were to be removed from the proximal end of the guidewire (as would permit advancement/retraction of a catheter thereover), such would result in deflation of the balloon, as the prior art balloon-on-a-wire systems do not incorporate any sort of check valve or other apparatus which would maintain inflation of the balloon even when the hub, stopcock and/or syringe used for inflation of the balloon has been removed from the proximal end of the guidewire.
In view of the state of the prior art, there exists a need for development of a flexible guidewire having an expandable or inflatable anchoring member (e.g. a balloon) disposed on the body thereof to anchor and hold the distal portion of the guidewire in a relatively fixed position while catheters, scopes or other instruments are advanced/retracted over the proximal end and/or body of the guidewire.